Magnetic read head having a cpp mr sensor electrically isolated from a top shield

ABSTRACT

An apparatus according to one embodiment includes an array of transducer structures arranged along a tape bearing surface of a common module. Each transducer structure includes a lower shield, an upper shield above the lower shield, a current-perpendicular-to-plane sensor between the upper and lower shields, at least one lead, and an insulating layer between the at least one lead and the shield closest thereto. The at least one lead is selected from a group including an upper electrical lead between the sensor and the upper shield, and a lower electrical lead between the sensor and the lower shield. The at least one lead is in electrical communication with the sensor. A width of one or more of the at least one lead in a cross track direction is about equal to a width of the sensor.

BACKGROUND

The present invention relates to data storage systems, and moreparticularly, this invention relates to magnetic heads such as tapeheads implementing current-perpendicular-to-plane (CPP) magnetoresistive(MR) sensors that are electrically isolated from top shields of the tapeheads.

In magnetic storage systems, magnetic transducers read data from andwrite data onto magnetic recording media. Data is written on themagnetic recording media by moving a magnetic recording transducer to aposition over the media where the data is to be stored. The magneticrecording transducer then generates a magnetic field, which encodes thedata into the magnetic media. Data is read from the media by similarlypositioning the magnetic read transducer and then sensing the magneticfield of the magnetic media. Read and write operations may beindependently synchronized with the movement of the media to ensure thatthe data can be read from and written to the desired location on themedia.

An important and continuing goal in the data storage industry is that ofincreasing the density of data stored on a medium. For tape storagesystems, that goal has led to increasing the track and linear bitdensity on recording tape, and decreasing the thickness of the magnetictape medium. However, the development of small footprint, higherperformance tape drive systems has created various problems in thedesign of a tape head assembly for use in such systems.

In a tape drive system, the drive moves the magnetic tape over thesurface of the tape head at high speed. Usually the tape head isdesigned to minimize the spacing between the head and the tape. Thespacing between the magnetic head and the magnetic tape is crucial andso goals in these systems are to have the recording gaps of thetransducers, which are the source of the magnetic recording flux in nearcontact with the tape to effect writing sharp transitions, and to havethe read elements in near contact with the tape to provide effectivecoupling of the magnetic field from the tape to the read elements.

BRIEF SUMMARY

An apparatus according to one embodiment includes an array of transducerstructures arranged along a tape bearing surface of a common module.Each transducer structure includes a lower shield, an upper shield abovethe lower shield, a current-perpendicular-to-plane sensor between theupper and lower shields, at least one lead, and an insulating layerbetween the at least one lead and the shield closest thereto. The atleast one lead is selected from a group including an upper electricallead between the sensor and the upper shield, and a lower electricallead between the sensor and the lower shield. The at least one lead isin electrical communication with the sensor. A width of one or more ofthe at least one lead in a cross track direction is about equal to awidth of the sensor.

An apparatus according to another embodiment includes an array oftransducer structures arranged along a tape bearing surface of a commonmodule. Each transducer structure includes a lower shield, an uppershield above the lower shield, a current-perpendicular-to-plane sensorbetween the upper and lower shields, an upper electrical lead betweenthe sensor and the upper shield, and an insulating layer between atupper electrical lead and the upper shield. The upper electrical lead isin electrical communication with the sensor. A width of the upperelectrical lead in a cross track direction is about equal to a width ofthe sensor.

A method of forming a plurality of magnetic head modules each having anarray of read transducer structures according to one embodiment includesforming a lower shield for each of the read transducer structures,forming a current-perpendicular-to-plane sensor above each lower shield,forming an upper electrical lead above each sensor, forming aninsulating layer above each upper electrical lead, and forming an uppershield above each insulating layer. Each upper electrical lead is inelectrical communication with the associated sensor. A width of eachupper electrical lead in a cross track direction is about equal to awidth of the sensor.

Any of these embodiments may be implemented in a magnetic data storagesystem such as a tape drive system, which may include a magnetic head, adrive mechanism for passing a magnetic medium (e.g., recording tape)over the magnetic head, and a controller electrically coupled to themagnetic head.

Other aspects and embodiments of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is a schematic diagram of a simplified tape drive systemaccording to one embodiment.

FIG. 1B is a schematic diagram of a tape cartridge according to oneembodiment.

FIG. 2 illustrates a side view of a flat-lapped, bi-directional,two-module magnetic tape head according to one embodiment.

FIG. 2A is a tape bearing surface view taken from Line 2A of FIG. 2.

FIG. 2B is a detailed view taken from Circle 2B of FIG. 2A.

FIG. 2C is a detailed view of a partial tape bearing surface of a pairof modules.

FIG. 3 is a partial tape bearing surface view of a magnetic head havinga write-read-write configuration.

FIG. 4 is a partial tape bearing surface view of a magnetic head havinga read-write-read configuration.

FIG. 5 is a side view of a magnetic tape head with three modulesaccording to one embodiment where the modules all generally lie alongabout parallel planes.

FIG. 6 is a side view of a magnetic tape head with three modules in atangent (angled) configuration.

FIG. 7 is a side view of a magnetic tape head with three modules in anoverwrap configuration.

FIG. 8A is a side view of a media facing side of a transducer structureaccording to one embodiment.

FIG. 8B is a side view of a media facing side of a transducer structureaccording to another embodiment.

FIG. 9 is a cross sectional view of the transducer structure of FIG. 8Ataken along line 9-9 of FIG. 8A.

FIG. 10 is a top down view of the transducer structure of FIG. 8A takenalong line 10-10 of FIG. 8A.

FIG. 11 is a cross sectional view of a transducer structure according toone embodiment.

FIG. 12 is a side view of a media facing side of a transducer structureaccording to one embodiment.

FIG. 13 is a diagram of a method according to one embodiment.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified.

The following description discloses several preferred embodiments ofmagnetic storage systems having one or more heads which implement CPP MRsensors that are electrically isolated from respective top shields ofthe heads. It follows that various embodiments described herein reducethe probability of sensor shorting, as will be described in furtherdetail below.

In one general embodiment, an apparatus includes a transducer structurehaving: a lower shield; an upper shield above the lower shield, theshields providing magnetic shielding; a current-perpendicular-to-planesensor between the upper and lower shields; at least one of an upperelectrical lead between the sensor and the upper shield and a lowerelectrical lead between the sensor and the lower shield, the at leastone lead being in electrical communication with the sensor; and aninsulating layer between the at least one of the leads and the shieldclosest thereto.

In another general embodiment, an apparatus includes a transducerstructure having: a lower shield; an upper shield above the lowershield; a current-perpendicular-to-plane sensor between the upper andlower shields; an upper electrical lead between the sensor and the uppershield, the upper electrical lead being in electrical communication withthe sensor; and an insulating layer between at upper electrical lead andthe upper shield.

In yet another general embodiment, a method of forming a transducerstructure includes forming a lower shield; forming acurrent-perpendicular-to-plane sensor above the lower shield; forming anupper electrical lead above the sensor, the upper electrical lead beingin electrical communication with the sensor; forming an insulating layerabove the upper electrical lead; and forming an upper shield above theinsulating layer.

FIG. 1A illustrates a simplified tape drive 100 of a tape-based datastorage system, which may be employed in the context of the presentinvention. While one specific implementation of a tape drive is shown inFIG. 1A, it should be noted that the embodiments described herein may beimplemented in the context of any type of tape drive system.

As shown, a tape supply cartridge 120 and a take-up reel 121 areprovided to support a tape 122. One or more of the reels may form partof a removable cartridge and are not necessarily part of the system 100.The tape drive, such as that illustrated in FIG. 1A, may further includedrive motor(s) to drive the tape supply cartridge 120 and the take-upreel 121 to move the tape 122 over a tape head 126 of any type. Suchhead may include an array of readers, writers, or both.

Guides 125 guide the tape 122 across the tape head 126. Such tape head126 is in turn coupled to a controller 128 via a cable 130. Thecontroller 128, may be or include a processor and/or any logic forcontrolling any subsystem of the drive 100. For example, the controller128 typically controls head functions such as servo following, datawriting, data reading, etc. The controller 128 may operate under logicknown in the art, as well as any logic disclosed herein. The controller128 may be coupled to a memory 136 of any known type, which may storeinstructions executable by the controller 128. Moreover, the controller128 may be configured and/or programmable to perform or control some orall of the methodology presented herein. Thus, the controller may beconsidered configured to perform various operations by way of logicprogrammed into a chip; software, firmware, or other instructions beingavailable to a processor; etc. and combinations thereof.

The cable 130 may include read/write circuits to transmit data to thehead 126 to be recorded on the tape 122 and to receive data read by thehead 126 from the tape 122. An actuator 132 controls position of thehead 126 relative to the tape 122.

An interface 134 may also be provided for communication between the tapedrive 100 and a host (integral or external) to send and receive the dataand for controlling the operation of the tape drive 100 andcommunicating the status of the tape drive 100 to the host, all as willbe understood by those of skill in the art.

FIG. 1B illustrates an exemplary tape cartridge 150 according to oneembodiment. Such tape cartridge 150 may be used with a system such asthat shown in FIG. 1A. As shown, the tape cartridge 150 includes ahousing 152, a tape 122 in the housing 152, and a nonvolatile memory 156coupled to the housing 152. In some approaches, the nonvolatile memory156 may be embedded inside the housing 152, as shown in FIG. 1B. In moreapproaches, the nonvolatile memory 156 may be attached to the inside oroutside of the housing 152 without modification of the housing 152. Forexample, the nonvolatile memory may be embedded in a self-adhesive label154. In one preferred embodiment, the nonvolatile memory 156 may be aFlash memory device, ROM device, etc., embedded into or coupled to theinside or outside of the tape cartridge 150. The nonvolatile memory isaccessible by the tape drive and the tape operating software (the driversoftware), and/or other device.

By way of example, FIG. 2 illustrates a side view of a flat-lapped,bi-directional, two-module magnetic tape head 200 which may beimplemented in the context of the present invention. As shown, the headincludes a pair of bases 202, each equipped with a module 204, and fixedat a small angle α with respect to each other. The bases may be“U-beams” that are adhesively coupled together. Each module 204 includesa substrate 204A and a closure 204B with a thin film portion, commonlyreferred to as a “gap” in which the readers and/or writers 206 areformed. In use, a tape 208 is moved over the modules 204 along a media(tape) bearing surface 209 in the manner shown for reading and writingdata on the tape 208 using the readers and writers. The wrap angle θ ofthe tape 208 at edges going onto and exiting the flat media supportsurfaces 209 are usually between about 0.1 degree and about 3 degrees.

The substrates 204A are typically constructed of a wear resistantmaterial, such as a ceramic. The closures 204B made of the same orsimilar ceramic as the substrates 204A.

The readers and writers may be arranged in a piggyback or mergedconfiguration. An illustrative piggybacked configuration comprises a(magnetically inductive) writer transducer on top of (or below) a(magnetically shielded) reader transducer (e.g., a magnetoresistivereader, etc.), wherein the poles of the writer and the shields of thereader are generally separated. An illustrative merged configurationcomprises one reader shield in the same physical layer as one writerpole (hence, “merged”). The readers and writers may also be arranged inan interleaved configuration. Alternatively, each array of channels maybe readers or writers only. Any of these arrays may contain one or moreservo track readers for reading servo data on the medium.

FIG. 2A illustrates the tape bearing surface 209 of one of the modules204 taken from Line 2A of FIG. 2. A representative tape 208 is shown indashed lines. The module 204 is preferably long enough to be able tosupport the tape as the head steps between data bands.

In this example, the tape 208 includes 4 to 22 data bands, e.g., with 16data bands and 17 servo tracks 210, as shown in FIG. 2A on a one-halfinch wide tape 208. The data bands are defined between servo tracks 210.Each data band may include a number of data tracks, for example 1024data tracks (not shown). During read/write operations, the readersand/or writers 206 are positioned to specific track positions within oneof the data bands. Outer readers, sometimes called servo readers, readthe servo tracks 210. The servo signals are in turn used to keep thereaders and/or writers 206 aligned with a particular set of tracksduring the read/write operations.

FIG. 2B depicts a plurality of readers and/or writers 206 formed in agap 218 on the module 204 in Circle 2B of FIG. 2A. As shown, the arrayof readers and writers 206 includes, for example, 16 writers 214, 16readers 216 and two servo readers 212, though the number of elements mayvary. Illustrative embodiments include 8, 16, 32, 40, and 64 activereaders and/or writers 206 per array, and alternatively interleaveddesigns having odd numbers of reader or writers such as 17, 25, 33, etc.An illustrative embodiment includes 32 readers per array and/or 32writers per array, where the actual number of transducer elements couldbe greater, e.g., 33, 34, etc. This allows the tape to travel moreslowly, thereby reducing speed-induced tracking and mechanicaldifficulties and/or execute fewer “wraps” to fill or read the tape.While the readers and writers may be arranged in a piggybackconfiguration as shown in FIG. 2B, the readers 216 and writers 214 mayalso be arranged in an interleaved configuration. Alternatively, eacharray of readers and/or writers 206 may be readers or writers only, andthe arrays may contain one or more servo readers 212. As noted byconsidering FIGS. 2 and 2A-B together, each module 204 may include acomplementary set of readers and/or writers 206 for such things asbi-directional reading and writing, read-while-write capability,backward compatibility, etc.

FIG. 2C shows a partial tape bearing surface view of complimentarymodules of a magnetic tape head 200 according to one embodiment. In thisembodiment, each module has a plurality of read/write (R/W) pairs in apiggyback configuration formed on a common substrate 204A and anoptional electrically insulative layer 236. The writers, exemplified bythe write transducer 214 and the readers, exemplified by the readtransducer 216, are aligned parallel to an intended direction of travelof a tape medium thereacross to form an R/W pair, exemplified by the R/Wpair 222. Note that the intended direction of tape travel is sometimesreferred to herein as the direction of tape travel, and such terms maybe used interchangeable. Such direction of tape travel may be inferredfrom the design of the system, e.g., by examining the guides; observingthe actual direction of tape travel relative to the reference point;etc. Moreover, in a system operable for bi-direction reading and/orwriting, the direction of tape travel in both directions is typicallyparallel and thus both directions may be considered equivalent to eachother.

Several R/W pairs 222 may be present, such as 8, 16, 32 pairs, etc. TheR/W pairs 222 as shown are linearly aligned in a direction generallyperpendicular to a direction of tape travel thereacross. However, thepairs may also be aligned diagonally, etc. Servo readers 212 arepositioned on the outside of the array of R/W pairs, the function ofwhich is well known.

Generally, the magnetic tape medium moves in either a forward or reversedirection as indicated by arrow 220. The magnetic tape medium and headassembly 200 operate in a transducing relationship in the mannerwell-known in the art. The piggybacked MR head assembly 200 includes twothin-film modules 224 and 226 of generally identical construction.

Modules 224 and 226 are joined together with a space present betweenclosures 204B thereof (partially shown) to form a single physical unitto provide read-while-write capability by activating the writer of theleading module and reader of the trailing module aligned with the writerof the leading module parallel to the direction of tape travel relativethereto. When a module 224, 226 of a piggyback head 200 is constructed,layers are formed in the gap 218 created above an electricallyconductive substrate 204A (partially shown), e.g., of AlTiC, ingenerally the following order for the R/W pairs 222: an insulating layer236, a first shield 232 typically of an iron alloy such as NiFe (-), CZTor Al—Fe—Si (Sendust), a sensor 234 for sensing a data track on amagnetic medium, a second shield 238 typically of a nickel-iron alloy(e.g., ˜80/20 at % NiFe, also known as permalloy), first and secondwriter pole tips 228, 230, and a coil (not shown). The sensor may be ofany known type of CPP sensor, including those based on magnetorisistive(MR), giant magnetorisistive (GMR), tunneling magnetoresistive (TMR),etc.

The first and second writer poles 228, 230 may be fabricated from highmagnetic moment materials such as ˜45/55 NiFe. Note that these materialsare provided by way of example only, and other materials may be used.Additional layers such as insulation between the shields and/or poletips and an insulation layer surrounding the sensor may be present.Illustrative materials for the insulation include alumina and otheroxides, insulative polymers, etc.

The configuration of the tape head 126 according to one embodimentincludes multiple modules, preferably three or more. In awrite-read-write (W-R-W) head, outer modules for writing flank one ormore inner modules for reading. Referring to FIG. 3, depicting a W-R-Wconfiguration, the outer modules 252, 256 each include one or morearrays of writers 260. The inner module 254 of FIG. 3 includes one ormore arrays of readers 258 in a similar configuration. Variations of amulti-module head include a R-W-R head (FIG. 4), a R-R-W head, a W-W-Rhead, etc. In yet other variations, one or more of the modules may haveread/write pairs of transducers. Moreover, more than three modules maybe present. In further approaches, two outer modules may flank two ormore inner modules, e.g., in a W-R-R-W, a R-W-W-R arrangement, etc. Forsimplicity, a W-R-W head is used primarily herein to exemplifyembodiments of the present invention. One skilled in the art apprisedwith the teachings herein will appreciate how permutations of thepresent invention would apply to configurations other than a W-R-Wconfiguration.

FIG. 5 illustrates a magnetic head 126 according to one embodiment ofthe present invention that includes first, second and third modules 302,304, 306 each having a tape bearing surface 308, 310, 312 respectively,which may be flat, contoured, etc. Note that while the term “tapebearing surface” appears to imply that the surface facing the tape 315is in physical contact with the tape bearing surface, this is notnecessarily the case. Rather, only a portion of the tape may be incontact with the tape bearing surface, constantly or intermittently,with other portions of the tape riding (or “flying”) above the tapebearing surface on a layer of air, sometimes referred to as an “airbearing”. The first module 302 will be referred to as the “leading”module as it is the first module encountered by the tape in a threemodule design for tape moving in the indicated direction. The thirdmodule 306 will be referred to as the “trailing” module. The trailingmodule follows the middle module and is the last module seen by the tapein a three module design. The leading and trailing modules 302, 306 arereferred to collectively as outer modules. Also note that the outermodules 302, 306 will alternate as leading modules, depending on thedirection of travel of the tape 315.

In one embodiment, the tape bearing surfaces 308, 310, 312 of the first,second and third modules 302, 304, 306 lie on about parallel planes(which is meant to include parallel and nearly parallel planes, e.g.,between parallel and tangential as in FIG. 6), and the tape bearingsurface 310 of the second module 304 is above the tape bearing surfaces308, 312 of the first and third modules 302, 306. As described below,this has the effect of creating the desired wrap angle α2 of the taperelative to the tape bearing surface 310 of the second module 304.

Where the tape bearing surfaces 308, 310, 312 lie along parallel ornearly parallel yet offset planes, intuitively, the tape should peel offof the tape bearing surface 308 of the leading module 302. However, thevacuum created by the skiving edge 318 of the leading module 302 hasbeen found by experimentation to be sufficient to keep the tape adheredto the tape bearing surface 308 of the leading module 302. The trailingedge 320 of the leading module 302 (the end from which the tape leavesthe leading module 302) is the approximate reference point which definesthe wrap angle α2 over the tape bearing surface 310 of the second module304. The tape stays in close proximity to the tape bearing surface untilclose to the trailing edge 320 of the leading module 302. Accordingly,read and/or write elements 322 may be located near the trailing edges ofthe outer modules 302, 306. These embodiments are particularly adaptedfor write-read-write applications.

A benefit of this and other embodiments described herein is that,because the outer modules 302, 306 are fixed at a determined offset fromthe second module 304, the inner wrap angle α₂ is fixed when the modules302, 304, 306 are coupled together or are otherwise fixed into a head.The inner wrap angle α₂ is approximately tan⁻¹ (δ/W) where δ is theheight difference between the planes of the tape bearing surfaces 308,310 and W is the width between the opposing ends of the tape bearingsurfaces 308, 310. An illustrative inner wrap angle α₂ is in a range ofabout 0.3° to about 1.1°, though can be any angle required by thedesign.

Beneficially, the inner wrap angle α₂ on the side of the module 304receiving the tape (leading edge) will be larger than the inner wrapangle α₃ on the trailing edge, as the tape 315 rides above the trailingmodule 306. This difference is generally beneficial as a smaller α₃tends to oppose what has heretofore been a steeper exiting effectivewrap angle.

Note that the tape bearing surfaces 308, 312 of the outer modules 302,306 are positioned to achieve a negative wrap angle at the trailing edge320 of the leading module 302. This is generally beneficial in helpingto reduce friction due to contact with the trailing edge 320, providedthat proper consideration is given to the location of the crowbar regionthat forms in the tape where it peels off the head. This negative wrapangle also reduces flutter and scrubbing damage to the elements on theleading module 302. Further, at the trailing module 306, the tape 315flies over the tape bearing surface 312 so there is virtually no wear onthe elements when tape is moving in this direction. Particularly, thetape 315 entrains air and so will not significantly ride on the tapebearing surface 312 of the third module 306 (some contact may occur).This is permissible, because the leading module 302 is writing while thetrailing module 306 is idle.

Writing and reading functions are performed by different modules at anygiven time. In one embodiment, the second module 304 includes aplurality of data and optional servo readers 331 and no writers. Thefirst and third modules 302, 306 include a plurality of writers 322 andno data readers, with the exception that the outer modules 302, 306 mayinclude optional servo readers. The servo readers may be used toposition the head during reading and/or writing operations. The servoreader(s) on each module are typically located towards the end of thearray of readers or writers.

By having only readers or side by side writers and servo readers in thegap between the substrate and closure, the gap length can besubstantially reduced. Typical heads have piggybacked readers andwriters, where the writer is formed above each reader. A typical gap is20-35 microns. However, irregularities on the tape may tend to droopinto the gap and create gap erosion. Thus, the smaller the gap is thebetter. The smaller gap enabled herein exhibits fewer wear relatedproblems.

In some embodiments, the second module 304 has a closure, while thefirst and third modules 302, 306 do not have a closure. Where there isno closure, preferably a hard coating is added to the module. Onepreferred coating is diamond-like carbon (DLC).

In the embodiment shown in FIG. 5, the first, second, and third modules302, 304, 306 each have a closure 332, 334, 336, which extends the tapebearing surface of the associated module, thereby effectivelypositioning the read/write elements away from the edge of the tapebearing surface. The closure 332 on the second module 304 can be aceramic closure of a type typically found on tape heads. The closures334, 336 of the first and third modules 302, 306, however, may beshorter than the closure 332 of the second module 304 as measuredparallel to a direction of tape travel over the respective module. Thisenables positioning the modules closer together. One way to produceshorter closures 334, 336 is to lap the standard ceramic closures of thesecond module 304 an additional amount. Another way is to plate ordeposit thin film closures above the elements during thin filmprocessing. For example, a thin film closure of a hard material such asSendust or nickel-iron alloy (e.g., 45/55) can be formed on the module.

With reduced-thickness ceramic or thin film closures 334, 336 or noclosures on the outer modules 302, 306, the write-to-read gap spacingcan be reduced to less than about 1 mm, e.g., about 0.75 mm, or 50% lessthan commonly-used LTO tape head spacing. The open space between themodules 302, 304, 306 can still be set to approximately 0.5 to 0.6 mm,which in some embodiments is ideal for stabilizing tape motion over thesecond module 304.

Depending on tape tension and stiffness, it may be desirable to anglethe tape bearing surfaces of the outer modules relative to the tapebearing surface of the second module. FIG. 6 illustrates an embodimentwhere the modules 302, 304, 306 are in a tangent or nearly tangent(angled) configuration. Particularly, the tape bearing surfaces of theouter modules 302, 306 are about parallel to the tape at the desiredwrap angle α₂ of the second module 304. In other words, the planes ofthe tape bearing surfaces 308, 312 of the outer modules 302, 306 areoriented at about the desired wrap angle α₂ of the tape 315 relative tothe second module 304. The tape will also pop off of the trailing module306 in this embodiment, thereby reducing wear on the elements in thetrailing module 306. These embodiments are particularly useful forwrite-read-write applications. Additional aspects of these embodimentsare similar to those given above.

Typically, the tape wrap angles may be set about midway between theembodiments shown in FIGS. 5 and 6.

FIG. 7 illustrates an embodiment where the modules 302, 304, 306 are inan overwrap configuration. Particularly, the tape bearing surfaces 308,312 of the outer modules 302, 306 are angled slightly more than the tape315 when set at the desired wrap angle α₂ relative to the second module304. In this embodiment, the tape does not pop off of the trailingmodule, allowing it to be used for writing or reading. Accordingly, theleading and middle modules can both perform reading and/or writingfunctions while the trailing module can read any just-written data.Thus, these embodiments are preferred for write-read-write,read-write-read, and write-write-read applications. In the latterembodiments, closures should be wider than the tape canopies forensuring read capability. The wider closures may require a widergap-to-gap separation. Therefore a preferred embodiment has awrite-read-write configuration, which may use shortened closures thatthus allow closer gap-to-gap separation.

Additional aspects of the embodiments shown in FIGS. 6 and 7 are similarto those given above.

A 32 channel version of a multi-module head 126 may use cables 350having leads on the same or smaller pitch as current 16 channelpiggyback LTO modules, or alternatively the connections on the modulemay be organ-keyboarded for a 50% reduction in cable span. Over-under,writing pair unshielded cables may be used for the writers, which mayhave integrated servo readers.

The outer wrap angles α₁ may be set in the drive, such as by guides ofany type known in the art, such as adjustable rollers, slides, etc. oralternatively by outriggers, which are integral to the head. Forexample, rollers having an offset axis may be used to set the wrapangles. The offset axis creates an orbital arc of rotation, allowingprecise alignment of the wrap angle α₁.

To assemble any of the embodiments described above, conventional u-beamassembly can be used. Accordingly, the mass of the resultant head may bemaintained or even reduced relative to heads of previous generations. Inother approaches, the modules may be constructed as a unitary body.Those skilled in the art, armed with the present teachings, willappreciate that other known methods of manufacturing such heads may beadapted for use in constructing such heads.

With continued reference to the above described apparatuses, it would beadvantageous for tape recording heads to include CPP MR sensortechnology, such as TMR and GMR. Furthermore, with the continualdecrease in data track width in magnetic storage technologies, CPP MRsensors enable readback of data in ultra-thin data tracks due to theirhigh level of sensitivity in such small operating environments.

As will be appreciated by one skilled in the art, by way of example, TMRis a magnetoresistive effect that occurs with a magnetic tunneljunction. TMR sensors typically include two ferromagnetic layersseparated by a thin insulating barrier layer. If the barrier layer isthin enough e.g., less than about 15 angstroms, electrons can tunnelfrom one ferromagnetic layer to the other ferromagnetic layer, passingthrough the insulating material and thereby creating a current.Variations in the current, caused by the influence of external magneticfields from a magnetic medium on the free ferromagnetic layer of the TMRsensor, correspond to data stored on the magnetic medium.

It is well known that TMR and other CPP MR sensors are very susceptibleto shorting during fabrication due to abrasive lapping particles thatscratch/smear conductive material across the insulating materialsseparating the conductive leads, e.g., opposing shields, therebycreating a short. Particularly, the lapping particles tend to plowthrough ductile magnetic material, e.g., from one or both shields,smearing the metal across the insulating material, and thereby creatingan electrical short that reduces the effective resistance of the sensorand diminishes the sensitivity of the sensor.

Scientists and engineers familiar with tape recording technology wouldnot expect a CPP MR sensor to remain operable (e.g., by not experiencingshorting) in a contact recording environment such as tape data storage,because of the near certain probability that abrasive asperitiesembedded in the recording medium will scrape across the thin insulatinglayer during tape travel, thereby creating the aforementioned shorting.

Typical CPP MR sensors such as TMR sensors in hard disk driveapplications are configured to be in electrical contact with the top andbottom shields of read head structures. In such configurations thecurrent flow is constrained to traveling between the top shield and thebottom shield through the sensor, by an insulator layer with a thicknessof about 3-100 nanometers (nm). This insulator layer extends below thehard magnet layer to insulate the bottom of the hard magnet from thebottom shield/lead layers, and isolates the edges of the sensor from thehard magnet material. In a tape environment, where the sensor is incontact with the tape media, smearing of the top or bottom shieldmaterial can bridge the insulation layer separating the hard magnet fromthe bottom lead and lower shield, thereby shorting the sensor.

In disk drives, conventional CPP MR designs are acceptable because thereis minimal contact between the head and the media. However, for taperecording, the head and the media are in constant contact. Head coatinghas been cited as a possible solution to these shorting issues; howevertape particles and asperities have been known to scratch through and/orwear away these coating materials. Furthermore, conventional magneticrecording head coatings do not protect against defects during lappingprocesses since the coating is applied after these process steps.Because the insulating layers of a conventional CPP MR sensor are sothin, the propensity for electrical shorting due, e.g., to scratches,material deposits, surface defects, etc. is extremely high. Embodimentsdescribed herein implement novel insulative layers on a CPP MR sensor inorder to prevent shorting in the most common areas where shorting hasbeen observed, e.g. the relatively larger areas on opposite sides of thesensor between the shields.

Furthermore, the potential use of CPP MR sensors in tape heads hasheretofore been thought to be highly undesirable, as tape heads includemultiple sensors, e.g., 16, 32, 64, etc., on a single die. If one ormore of those sensors become inoperable due to the aforementionedshorting, the head becomes defective and typically would need to bediscarded and/or replaced for proper operation of the apparatus.

Conventional current in plane-type sensors require at least two shortingevents across different parts of the sensor in order to affect thesensor output, and therefore such heads are far less susceptible toshorting due to scratches. In contrast, tape heads with CPP MR sensorsmay short with a single event, which is another reason that CPP MRsensors have not been adopted into contact recording systems.

Various embodiments described herein have top and/or bottom shieldselectrically isolated from a CPP MR sensor, thereby eliminate theproblem of shield-to-shield shorting rendering the sensor diminishedand/or inoperative.

FIG. 8A depicts a transducer structure 800 in accordance with oneembodiment. As an option, the present transducer structure 800 may beimplemented in conjunction with features from any other embodimentlisted herein, such as those described with reference to the other FIGS.Of course, however, such transducer structure 800 and others presentedherein may be used in various applications and/or in permutations whichmay or may not be specifically described in the illustrative embodimentslisted herein. Further, the transducer structure 800 presented hereinmay be used in any desired environment.

Referring now to FIG. 8A, transducer structure 800 includes a lowershield 810 and an upper shield 804 above the lower shield 810, theshields providing magnetic shielding. Transducer structure 800 furtherincludes a CPP MR, e.g. such as a TMR sensor, GMR sensor, etc. Betweenthe upper and lower shields 804, 810, transducer structure 800 includessensor stack 818. An upper electrical lead 808 is positioned between thesensor stack 818 and the upper shield 804. Additionally, transducerstructure 800 includes a hard bias layer 814 and a hard bias insulatinglayer 816. The hard bias insulating layer 816 insulates the sensor stack818 from the hard bias layer 814. The sensor stack 818 and the hard biaslayer 814 are separated by a hard bias insulating layer 816 width in thewidth direction W of about 3-100 nm. The hard bias insulating layer 816additionally extends below the hard bias layer 814 to insulate thebottom of the hard bias layer 814 from the top of the lower electrode,which may be the lower shield 810 as in FIG. 8B, and/or an optionallower lead 812 as in FIG. 8A.

As briefly described above, the lower electrical lead 812 is positionedbetween the sensor stack 818 and the lower shield 810. The upperelectrical lead 808 and lower electrical lead 812 are in electricalcommunication with the sensor stack 818. Note that the transducerstructure 800 and additional transducer structures described herein mayinclude more than one upper and/or lower electrical leads, depending onthe embodiment. An insulating layer 806 is positioned between the upperelectrical lead 808 and the shield closest thereto e.g. the upper shield804.

In embodiments described herein, an insulating layer e.g. insulatinglayer 806 is positioned between e.g. at least one of the leads, any ofthe leads, all of the leads, etc. and the shield closest to therespective lead thereto, such that the at least one lead is electricallyisolated from the shield closest thereto. Insulating layer 806 may beconstructed of any suitable electrically insulating material, such asalumina, alumina oxide, SiO₂, TaO₂, Si₃N₄, etc., depending on theembodiment.

Some embodiments described herein include an optional insulating layer802 as shown e.g. in FIGS. 8A and 9-12. The optional insulating layer802 is illustrated as being positioned below the upper electrical lead808, sandwiched between the upper electrical lead 808 and the nearesthard bias layer 814. However, the position of the insulating layer 802may vary depending on the preferred embodiment.

As described above, it is not uncommon for tape asperities passing overthe sensor to smear the material of an upper or lower shield onto theopposite shield, thereby potentially shorting the sensor. Insulatinglayer 806 reduces the probability of smear in the sensor regionparticularly by increasing the spacing between the upper and lowershield 804, 810. Moreover, because the upper lead 808 is isolated fromthe upper shield 804 by the insulating layer 806, and preferably has awidth that is less than the width of the upper shield 804, theprobability of a smear bridging the upper and lower leads 808, 812 isminimized.

The shield to shield spacing t2 is selected based on the linearrecording density of the format, and therefore generally cannot simplybe made larger to prevent shorting. Moreover, it would be desirable tomaximize the thickness of the insulating layer 806 while minimizing thethickness of the upper lead 808; however, the lead cannot be too thin asthis would raise head resistance and hurt sensitivity. Accordingly, abalance between layer thicknesses within the constraint of the spacingt2 is desirable. Insulating layer 806 preferably has a thickness t1 ofabout 5-25 nanometers, but could be greater or less in otherembodiments. Due to the insertion of the insulating material within theshield to shield spacing t2, the probability of a smearing event fromplowing material of one shield to the other shield in a thicknessdirection T (which would ultimately short the sensor) is decreased.Direction T may also be herein referred to as the intended direction oftape travel.

Although not illustrated in transducer structure 800, according tovarious embodiments, a lower insulating layer may be present between thelower shield 810 and the lower lead 812 (as will be further described inFIG. 12). For example, one embodiment may have a lower lead and a lowerinsulating layer therebelow, while the upper lead 808 is electricallycoupled to the upper shield 804, e.g., insulating layer 806 is notpresent. In embodiments having both upper and lower insulating layers,the probability of a smearing event from plowing material of one shieldto the other shield in direction T (which would ultimately short thesensor) is decreased even further.

The upper lead 808 and the lower lead 812 are preferably constructed ofany suitable conductive material e.g., Jr, Ru, NiCr, Ta, Cr, etc., maybe a laminated structure of Ta e.g. Ta/X/Ta, etc. Furthermore, thecompositions of the upper lead 808 and the lower lead 812 may be thesame or different, and may vary depending on the embodiment.

According to one embodiment, as illustrated in FIG. 8B, the upper and/orlower leads 808, 812 may have a width that is about equal to the widthof the sensor stack 818, and in other embodiments up to about 300% widerthan the width of the sensor stack 818. According to another embodiment(e.g. see FIGS. 8A, 9, 11 and 12, etc.) the upper and/or lower lead 808,812 may have a width that is substantially greater than the width of thesensor stack 818. Furthermore, the upper and lower leads 808, 812 mayhave different thicknesses or the same thicknesses, depending on e.g.the embodiment, system constraints, etc.

Referring now to FIG. 9, there is shown a cross sectional view oftransducer structure 800 of FIG. 8A, including electrical vias 902, 903(not shown in FIG. 8A). As illustrated in FIG. 9 the electrical vias902, 903 are positioned behind the upper shield 804, relative to themedia facing side 904 of the upper shield 804 in the height direction H.Additionally, electrical vias 902, 903 are each in electricalcommunication with one of the leads e.g. upper lead 808 (as shown inFIG. 9) and lower lead 812, respectively. As depicted, the electricalvia 902 is isolated from the shield, e.g. upper shield 804, closestthereto. Electrical via 903 is electrically isolated from upper lead 808and is in electrical communication with the lower lead 812. In order forthe electrical via 902 to be in electrical communication with the upperlead 808 (as shown in FIG. 9), the upper lead 808 extends past the backedge 906 of the upper shield 804. The electrical vias 902, 903 mayextend to pads on the head, which may ultimately be coupleable to acable for communication with drive circuitry.

It should be noted that ‘lower’ and ‘upper’ implemented in descriptionsherein generally correspond to order of fabrication, e.g. a lower shield810 being formed before a corresponding upper shield 804, etc. Methodsof fabrication and manufacture will be described below.

FIG. 10 illustrates a top down view of the transducer structure 800 ofFIG. 8A. As was described in FIG. 9, the upper lead 808 in FIG. 10 isseen extending past the back edge 906 of the upper shield 804 and is inelectrical communication with electrical via 902.

FIG. 11, which may otherwise have similar components as otherembodiments herein, includes a transducer structure 1100 where one ofthe leads e.g. stitched lead 1102 isolated from the shield closestthereto e.g. upper shield 804, includes a main layer 1108 and a stitchlayer 1106. By stitching a second layer of lead material e.g. stitchlayer 1106, that is recessed past the back edge 906 of the sensor stack818, the resistance associated with the routing of the upper lead 808past the back edge of the upper shield 804 is reduced. Additionally, thestitch layer 1106 is recessed from a media facing side 904 of the mainlayer 1108. The stitched lead 1102 may be constructed of any suitableconductive material, such as Jr, Cu, Ru, Pt, NiCr, Au, Ag, Ta, Cr, etc.;may be a sandwich structure of Ta e.g. Ta/X/Ta; etc.

The stitched lead configuration of transducer structure 1100 desirablyreduces the resistance associated with the routing of the upper lead 808past the back edge 906 of the upper shield 804. For example, in anembodiment where Ru is used as the top lead material, the resistivity“ρ” would be about 7.1 micro-ohms/cm. A single lead with thickness of 30nm would have a sheet resistivity (p/thickness) equal to about 2.3ohms/square. This implies that if the top lead design had 6 “squares” oflead geometry, the lead resistance would be about 13.8 ohms. However, byimplementing a stitched lead 1102 above the top lead, the total leadresistance would be significantly reduced. For example, consider astitched lead of Ru with a thickness of 45 nm covering 5 of the 6“squares” of the lead geometry. The lead region where the stitchedstructure and the initial lead overlay has a net thickness of about 75nm and a sheet resistivity equal to 0.95 ohms/square. Implementing astitched lead 1102 as described above would reduce the lead resistanceto 7.3 ohms or by about 45%. Embodiments described herein may or may notimplement the stitched lead 1102, depending on the preferred embodiment.

FIG. 12 depicts transducer structure 1200 in accordance with oneembodiment. As an option, the present transducer structure 1200 may beimplemented in conjunction with features from any other embodimentlisted herein, such as those described with reference to the other FIGS.Of course, however, such transducer structure 1200 and others presentedherein may be used in various applications and/or in permutations whichmay or may not be specifically described in the illustrative embodimentslisted herein. Further, the transducer structure 1200 presented hereinmay be used in any desired environment.

Transducer structure 1200 includes a similar transducer structure toe.g. transducer structure 850 (and 800), with a few differences. Forexample, transducer structure additionally includes a lower insulatinglayer 1202, which is positioned between the lower lead 812 and the lowershield 810, such that the lower lead 812 is electrically isolated fromthe shield closest thereto e.g. lower shield 810. Sensor stack 818 iselectrically isolated in transducer structure 1200 from the upper shield804 and the lower shield 810 by the insulating layer 806 and the lowerinsulating layer 1202, respectively. Furthermore, the lower lead 812 isillustrated as being wider than the sensor stack 818, but as describedabove, according to preferred embodiments the lower lead 812 width mayhave a similar width as the sensor stack 818. Similarly, the upper lead808 is illustrated as having a width about equal to the sensor stack 818width, but according to other embodiments, the upper lead 808 may have awidth that is greater than the sensor 818 width.

Lower insulating layer 1202 may be constructed of any suitableinsulating material, such as alumina, alumina oxide, SiO₂, TaO₂, Si₃N₄,etc. Transducer structure thickness ranges will now be described below.

The read gap of transducer structure 1200 includes the lower lead 812,the lower insulating layer 1202 (for transducer structure 1200), thesensor stack 818, the upper lead 808, and the upper insulating layer806. In order to reduce the lower lead 812 resistance, a partialmajority of the read gap thickness is allocated to the lower lead 812,and thus the lower lead 812 thickness can range from about 5-35 nm andthe lower insulating layer 1202 can range from about 5-25 nm, but eitherrange could be higher or lower. Furthermore, the sensor stack 818typically has a thickness in direction T of about 45 nm. In order toreduce the upper lead 808 resistance, a partial majority of the read gapthickness is allocated to the upper lead 808, and thus the upper lead808 thickness can range from about 5-35 nm and the upper insulatinglayer 806 can range from about 5-25 nm, but could be higher or lower.

According to the above described transducer layer thicknesses,transducer structures with an upper insulating layer 806 and no lowerinsulating layer 1202 (e.g. transducer structures 800, 850, 1100, etc.)may have a read gap thickness (shield to shield spacing) t2 in directionT of about 85-125 nm, but could be higher or lower. Thicknessesdescribed above are measured in the tape travel direction T, and mayvary depending on the linear density of the recording format.

A method of manufacture of the above described transducer structureswill now be described below. The implementation of upper insulatinglayer 806, and depending on the embodiment, the lower insulating layer1202 decreases the probability of a smearing event from plowing materialof a shield across multiple leads in a direction T (which wouldultimately short the sensor).

FIG. 13 depicts method 1300 in accordance with one embodiment. As anoption, the present method 1300 may be implemented in conjunction withfeatures from any other embodiment listed herein, such as thosedescribed with reference to the other FIGS. Of course, however, suchmethod 1300 and others presented herein may be used in variousapplications and/or in permutations which may or may not be specificallydescribed in the illustrative embodiments listed herein. Further, themethod 1300 presented herein may be used in any desired environment.

Referring now to method 1300, operations 1302, 1304, 1306, 1308, and1310 describe a method of manufacture of embodiments e.g. transducerstructures, etc. described herein. Operation 1302 of method 1300includes forming a lower shield (e.g. lower shield 810 of FIGS. 8A-12),etc. Operation 1304 includes forming a current-perpendicular-to-planesensor e.g. such as a TMR sensor above the lower shield 810.

With continued reference to method 1300, operation 1306 includes formingan upper electrical lead above the sensor (e.g. see 808 of FIGS. 8A-12),where the upper electrical lead is in electrical communication with thesensor. Operation 1308 includes forming an insulating layer above theupper electrical lead. Additionally, operation 1310 includes forming anupper shield above the insulating layer.

Various embodiments may be fabricated using known manufacturingtechniques. Conventional materials may be used for the various layersunless otherwise specifically foreclosed. Furthermore, as describedabove, deposition thicknesses, configurations, etc. may vary dependingon the embodiment.

It should be noted that although FIGS. 8A-12 each illustrate a singletransducer structure (transducer structures 800, 850, 1100, 1200),various embodiments described herein include at least eight of thetransducer structures above a common substrate, e.g., as shown in FIG.2B. Furthermore, the number of transducer structures in a given arraymay vary depending on the preferred embodiment.

It will be clear that the various features of the foregoing systemsand/or methodologies may be combined in any way, creating a plurality ofcombinations from the descriptions presented above.

It will be further appreciated that embodiments of the present inventionmay be provided in the form of a service deployed on behalf of acustomer.

The inventive concepts disclosed herein have been presented by way ofexample to illustrate the myriad features thereof in a plurality ofillustrative scenarios, embodiments, and/or implementations. It shouldbe appreciated that the concepts generally disclosed are to beconsidered as modular, and may be implemented in any combination,permutation, or synthesis thereof. In addition, any modification,alteration, or equivalent of the presently disclosed features,functions, and concepts that would be appreciated by a person havingordinary skill in the art upon reading the instant descriptions shouldalso be considered within the scope of this disclosure.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of an embodiment of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the followingclaims and their equivalents.

What is claimed is:
 1. An apparatus, comprising: an array of transducerstructures arranged along a tape bearing surface of a common module,each transducer structure having: a lower shield; an upper shield abovethe lower shield; a current-perpendicular-to-plane sensor between theupper and lower shields; at least one lead selected from a groupconsisting of: an upper electrical lead between the sensor and the uppershield and a lower electrical lead between the sensor and the lowershield, the at least one lead being in electrical communication with thesensor; and an insulating layer between the at least one lead and theshield closest thereto, wherein a width of one or more of the at leastone lead in a cross track direction is about equal to a width of thesensor.
 2. An apparatus as recited in claim 1, wherein the upperelectrical lead is present in each transducer structure, wherein theinsulating layer is present between the upper shield and the upperelectrical lead.
 3. An apparatus as recited in claim 1, wherein thelower electrical lead is present in each transducer structure, whereinthe insulating layer is present between the lower shield and the lowerelectrical lead.
 4. An apparatus as recited in claim 1, wherein theupper and lower electrical leads are present in each transducerstructure, wherein the insulating layer is present between the uppershield and the upper electrical lead, wherein the insulating layer ispresent between the lower shield and the lower electrical lead.
 5. Anapparatus as recited in claim 1, wherein, for each transducer structure,one of the leads isolated from the shield closest thereto includes amain layer and a stitch layer thereon, the stitch layer being recessedfrom a media facing side of the main layer.
 6. An apparatus as recitedin claim 1, comprising, in each transducer structure, an electrical viapositioned behind the upper shield relative to a media facing side ofthe upper shield, the electrical via being in electrical communicationwith one of the leads isolated from the shield closest thereto.
 7. Anapparatus as recited in claim 1, wherein the upper electrical lead ispresent, and comprising an insulating layer sandwiched between the upperelectrical lead and a hard bias layer.
 8. An apparatus as recited inclaim 1, wherein each sensor is a tunneling magnetoresistive sensor. 9.An apparatus as recited in claim 8, wherein at least eight of thetransducer structures are present above a common substrate.
 10. Anapparatus as recited in claim 9, comprising: a drive mechanism forpassing a magnetic medium over the sensors; and a controllerelectrically coupled to the sensor.
 11. An apparatus as recited in claim10, wherein the magnetic medium is a magnetic recording tape, andcomprising, in each transducer structure, an electrical via positionedbehind the upper shield relative to a media facing side of the uppershield, the electrical via being in electrical communication with one ofthe leads isolated from the shield closest thereto.
 12. An apparatus,comprising: an array of transducer structures arranged along a tapebearing surface of a common module, each transducer structure having: alower shield; an upper shield above the lower shield; acurrent-perpendicular-to-plane sensor between the upper and lowershields; an upper electrical lead between the sensor and the uppershield, the upper electrical lead being in electrical communication withthe sensor; and an insulating layer between at upper electrical lead andthe upper shield, wherein a width of the upper electrical lead in across track direction is about equal to a width of the sensor.
 13. Anapparatus as recited in claim 12, comprising a lower electrical leadbetween each lower shield and the associated sensor, wherein each lowerelectrical lead is in electrical communication with the associated lowershield and the associated sensor.
 14. An apparatus as recited in claim12, comprising an electrical via in each transducer structure, theelectrical via being positioned behind the upper shield relative to amedia facing side of the upper shield, the electrical via being inelectrical communication with the upper electrical lead, and comprisinga lower electrical lead in electrical communication with the sensor, thelower electrical lead being positioned between the sensor and the lowershield, wherein a width of the lower electrical lead in the cross trackdirection is greater than the width of the sensor, wherein the lowerelectrical lead is electrically isolated from the lower shield.
 15. Anapparatus as recited in claim 12, comprising: a drive mechanism forpassing a magnetic medium over the sensors; and a controllerelectrically coupled to the sensors.
 16. An apparatus as recited inclaim 15, wherein the magnetic medium is a magnetic recording tape. 17.An apparatus as recited in claim 12, wherein each sensor is a tunnelingmagnetoresistive sensor, wherein at least eight of the transducerstructures are present above a common substrate.
 18. A method of forminga plurality of magnetic head modules each having an array of readtransducer structures, the method comprising: forming a lower shield foreach of the read transducer structures; forming acurrent-perpendicular-to-plane sensor above each lower shield; formingan upper electrical lead above each sensor, each upper electrical leadbeing in electrical communication with the associated sensor; forming aninsulating layer above each upper electrical lead; and forming an uppershield above each insulating layer, wherein a width of each upperelectrical lead in a cross track direction is about equal to a width ofthe sensor.
 19. A method as recited in claim 18, comprising forming alower electrical lead between each lower shield and the associatedsensor, wherein each upper electrical lead includes a main layer and astitch layer thereon, the stitch layer being recessed from a mediafacing side of the main layer, wherein a width of each lower electricallead in the cross track direction is greater than a width of theassociated sensor.
 20. A method as recited in claim 18, wherein eachsensor is a tunneling magnetoresistive sensor.